2-Ester-substituted-3,4-dihydro-3-oxo-quinoxalines are described as antiviral agents in copending application Ser. No. 953,157, filed Oct. 20, 1978, now abandoned, in Ser. No. 60,445 filed July 25, 1979, now abandoned, and in Ser. No. 88,274, filed Oct. 25, 1979, now U.S. Pat. No. 4,264,600, issued Apr. 28, 1981. The compounds are particularly useful in that they show antiviral activity against both A and B strains of influenza virus. The antiviral activity of 1-aminoadamantane (amantidine, adamantylamine) was first disclosed by Davies et al. Science, 144,862 (1964). 1-aminoadamantane is said to be active against influenza virus A.sup.2 strain prophylactically. The compound also may have some use in the prophylaxis of Asian flu strains antigenically related to strain A.sup.2. 3-Methyl-1-aminoadamantane, dl-cyclooctylamine, 2-norbornylamine and 1-adamantyl-1-aminoethane (rimantadine) have all been shown to be antiviral agents, both by myself and those working with me and by those working in other laboratories.